Furnace for smelting ores



(No Model.) -E. E. LUNGW-ITZ.

FURNACE FOR SMELI'IN-Gv ORES.

N0. 555,961. Patented Mar. 10, 1896..

WlTNESSES: INVENTOIR fl v @WQ llammfik ATTORNEYS.

EMIL E. LUNGIVITZ, OF

BROOKLYN, NEW YORK.

FURNACE FOR SMELTING ORES.

SPECIFICATION forming part of Letters Patent No. 555,961, dated. March10, 1896. Original application filed December 3, 1892, Serial No.453,993. Divided and this application filed October 1, 1894. Serial No.

To all whom it may concern.-

Be it known that I, EMIL E. LUNGWITZ, a citizen of the United States ofAmerica, residing at Brooklyn, county of Kings, and State of New York,have invented certain new and useful Improvements in Furnaces forSmelting Ores, of which the following is a specification.

The present invention relates to an improved furnace for smelting ores;and it has for its object to provide means for cooling the walls of thefurnace and maintaining an external pressure thereon equal to the internal pressure.

The present case is a division of my application filed December 3, 1892,Serial No. 453, 993, in which the process herein described is claimed.

It is well known that the boiling-point of a substance depends upon thepressure exerted upon the liquid, the boiling-point rising with thepressure according to a law governed by the nature of the substance.Sufficient pressure will prevent ebullition of a liquid, even if itstemperature be raised considerably be-' yond its boiling-point underordinary press ure. To prevent volatilization of the regulus once formedit is only necessary to maintain a sufficiently high pressure in thefurnace. In the case of an ore containinglead and zinc oxides, forinstance, the zinc would volatilize at the temperature of thefurnace-say 1,200 centigrade-if a sufficient pressure were not exertedto raise its boiling-point to this temperature. From the researches ofDr. Carl Barns (Bulletin United States GeologicalSurvey No. 54, 1889,and confirmed by my own investigation) we may conclude that the tensionof zinc-vapor at this temperature would be about fifty pounds.

In the accompanying drawing is shown a central vertical section of ablastfurnace illustrating one means for carrying my invention intoeffect.

A represents the steel or similar casing of the stack supporting andinclosing the firebrick B. The throat of the furnace is closed by a capor plate O, having an opening con trolled by a trap-door O, hinged tothe under side of the cap. This opening is preferably centrally located,but may be placed to- (No model.)

ward the side of the throat if desired. The usual hopper D for feedingore and fuel is inserted in the throat of the furnace. Thedischarge-openin g in this hopper is controlled by a trap-door D, hingedto the under side of the hopper. The trap-doors O and D may, if desired,be replaced by ordinary bellclosures. Tuyeres E of the usualconstruction supply the blast for raising the temperature and also forraising the pressure within the furnace, so that the reduced metal or0X- ides will not boil under the temperature necessary for conductingthe process.

F is a second steel or other casing surrounding the casing A. The spacebetween these two casings forms a water and air tight chamber in whichwater is kept circulating to cool the casing A, and to prevent injury tosaid casing, if it should become exposed to the pressure Within thefurnace through fusing of the fire-brick at any point, the water in saidchamber is kept under pressure equal to the pressure within the furnace.Water is supplied to this cooling-chamber through the nozzles g of thepipes G, leading from the bustlepipe G by any suitable pump, the waterentering preferably near the throat of the furnace and descending to thehearth, thus cooling the upper portion of the stack first and beingheated gradually as it approaches the heartlnwhere it escapes through asuitable discharge-pipe G. may be utilized by feeding it directly to theboiler connected with the engine supplying the blast for the furnace.Suitable pressuregages H and II are applied to the furnace to indicatethe pressure exerted within the f urnace and the cooling-chamberrespectively, in order that said pressures may be kept equal.Safety-valves I and I may also be applied to the furnace and thecooling-chamber respectively, to balance the pressures by removing anyexcess in either. The furnace safety-valve I is preferably located justbelow the trap-door D, and through it the waste gases are discharged.The construction of this valve is similar to that of a boilersafetyvalve.

The operation of my invention is as follows: A charge of fuel and ore isintroduced into the furnace through the openings in the plate This hotwater 7 C and hopper D, after which the trap-doors O and D are closed.After the fires are started the blast is turned on through the tuyeres Euntil the pressure within the furnace exceeds the pressure at which themetal to be reduced would boil at the temperatures to be created by theblast. As soon as the ore is smelted the reduced metal sinks to thehearth, where it collects and may be drawn off through the tap-hole.Volatilization of the metal or regulus and of the oxides is thusprevented, as the pressure exerted upon the charge is so high that itcannot boil, and hence cannot volatilize and be carried off through thefurnace throat, or over into the flue-dust chamber. This is a feature ofgreat importance, as the metal once reduced sinks to the hearth, and isnot carried off by the flue to be returned through the hopper in theform of an oxide and resmelted. Besides, by the expansion of the blastin furnaces as at present constructed the finer particles of the chargeare carried over into the flue-dust chamber, as the blast maintains itspressure only at the tuyeres. As any desired pressure is maintainedconstant throughout the fur nace in my invention, however, the formationof flue-dust is almost entirely prevented.

The construction of furnace I have illustrated is especially designedfor continuous smelting and roasting without lowering the pressurewithin the furnace. When it be comes necessary to recharge the furnacethe trap-door O (or bell, as the case may be) is opened and fuel or orefed into the hopper, the trap-doorD (or bell) being kept closed. When asufficient quantity of the charge has thus been introduced into thehopper,the door 0 is closed and I) is opened, when the fuel or oreenters the furnace, the door D being closed after all the charge hasbeen fed to the furnace by the hopper. It will be seen that while thusrecharging the furnace none of its gaseous contents can escape, and thepressure remains undisturbed, as one of the exits is always closed andthe inclosed gases cannot get beyond the cap or plate 0 of the stack.

My process is applicable not only to the smelting and roasting of orescontaining a single metallic element, but to ores containing severalsuch elements. The pressure of the blast would of course depend upon themetal or metals to be reduced and to be oxidized from the ore, and whereseveral metals are reduced and roasted simultaneously within the furnacethe pressure would be sufficiently high to prevent volatilization of themetal to be tapped.

I do not wish to be understood as limiting myself to any specific meansfor regulating and balancing the pressures in the furnace and.cooling-chamber, respectively, as the means so employed may be modifiedwithout departing from the spirit of the invention.

No claim is herein made to the process of roasting ores, as the sameforms the subjectmatter of an application filed by me June 15, 1893,Serial No. 477,714.

Vhat is claimed is 1. The herein-described blast-furnace stack closed tothe atmosphere, means for maintaining within the stack a pressure higherthan that at which the volatilizable metal or metals contained in theore to be smelted would boil at the temperature of the furnace, a closedcasing surrounding said stack and forming with its exterior walls anair-tight chamber, and means for exerting and maintaining in saidchamber a pressure substantially equal to the pressure maintained withinthe stack, as described.

2. The herein-described blast-furnace stack closed to the atmosphere,means for maintaining within the stack a pressure higher than that atwhich the Volatilizable metal or metals contained in the ore to besmelted would boil at the temperature of the furnace, a closed casingsurrounding said stack and forming with its exterior walls an air-tightchamber and means for supplying and maintaining in said chamber a fluidat a pressure substantially equal to the pressure main tained within thestack, as described.

In witness whereof I have hereunto signed my name in the presence of twowitnesses.

EMIL E. LUNGWIT'... Witnesses:

ROBERT C. SoHiiPPHAus, E. L. Tom).

